The present invention relates to an oil rotary vacuum pump of mechanical type and to a method of manufacturing such pump.
Oil rotary pumps of mechanical type are generally used to obtain low vacuum conditions, in a pressure range from atmospheric pressure to about 10−1 Pa.
Typical mechanical pumps include a casing, having a suction port and an exhaust port, within which a stator is provided defining a cylindrical chamber housing an eccentric circular rotor equipped with spring-loaded radial vanes. Said pumps are immersed into an oil bath, which has to cool down and lubricate the pump and isolate the pump from the outside environment.
Pumps of such kind are known for instance from the U.S. Pat. No. 6,019,585 “Oil-Sealed Vane-Type Rotary Vacuum Pump With Oil Feed” and the GB Patent Application No.2151091A “Electric Drive for Oil Sealed Sliding Vane Rotary Vacuum Pump.”
According to the prior art, manufactured pumps are stored and subsequently shipped to the user without oil inside them. Thus, it is up to the user, who often has no skill in the art, to introduce the proper amount of oil into the pump prior to the first use.
It is clear that such a way of proceeding has a serious drawback: indeed, if the user does not perform the oil filling of the pump properly, severe risks of damaging the pump are encountered, in particular because of seizure of the moving parts due to the lack or insufficiency of lubricant.
Therefore, it is an object of the present invention to obviate the above-identified drawback, by providing an oil rotary pump of mechanical type, which can be filled with the proper amount of oil at the end of the manufacturing process and shipped to the user in such conditions.
It is another object of the present invention to provide an oil rotary pump of mechanical type already containing the proper amount of oil, which pump can be stored for any period of time and subsequently shipped to the user without any risk of the oil coming out or undergoing degradation.